2-Ethoxymethyl salvinorin B (symmetry, 2-EtOMe-Sal B) is a semi-syntheticanalogue of the natural product salvinorin A, with a longer duration of action of around 3 hours (compared to less than 30 minutes for salvinorin A), and increased affinity and intrinsic activity at the κ-opioidreceptor. Like the related compound herkinorin, 2-ethoxymethyl salvinorin B is made from salvinorin B, which is most conveniently made from salvinorin A by deacetylation,[1] as while both salvinorin A and salvinorin B are found in the plant Salvia divinorum, salvinorin A is present in larger quantities.[2]

2-Ethoxymethyl salvinorin B has a Ki of 0.32 nM at the κ-opioid receptor, and around 3,000 times selectivity over the μ- and δ-opioid receptors, making it one of the most potent and selective kappa agonists yet discovered.[3] In animal studies it fully substituted for salvinorin A and the synthetic kappa agonist U-69593, and was active at doses as low as 0.005 mg/kg.[4] Human bioassays found the compound to be active at 50 μg, but generally unpleasant in effects.[5]